This invention relates to interference filters having adjacent silicon oxide-silver layers and, more particularly, to such filters having bonding between the layers enhanced by a very thin metal film.
Infrared reflecting filters having adjacent refractory dielectric-silver coatings have recently been discovered. Such filters are described in detail in the copending application of Leei Chang entitled, "Infrared Reflecting Articles," Ser. No. 892,585 filed Apr. 3, 1978, and now U.S. Pat. No. 4,179,181. The articles are made by vapor depositing one or more three-coating periods. Each period has a layer of silver sandwiched between two layers of a refractory oxide. Suitable refractory dielectrics disclosed include silicon oxides having the formula SiO.sub.x, where x is from 1 to 2. The application further discloses that palladium enhances the bond between the SiO.sub.x and silver layers. However, palladium has the disadvantage of substantially reducing the visible transmission, even when used in films as thin as 5 A, as well as being very expensive.